[GAMEPLAY] Summoner Spells Not Activating

So this has been an issue I've noticed ever since 5.3 went live. It happens in all game mode and with all summoner spells as far as I can tell. The issue is as the title says, my summoner spells occasionally will not activate when I hit the hotkeys for them. My UI will show that they're off cooldown, but when I hit the buttons, nothing will happen. This happens on both targeted and non-targeted spells. It doesn't happen all of the time, but it seems to be more random than anything when it does occur.

At first I thought it might have been a UI glitch where the icon was showing as off cooldown but wasn't actually off cooldown yet, but then I started to actually keep note of the timers more closely and determined that wasn't the case. The other potential problem I thought of was very quickly debunked because it was a theory that maybe my 'D' and 'F' keys on my keyboard are bad. And as you can see through this post alone, that's not the case since I have typed numerous 'D's and 'F's with no issue. My third theory was that it might have been happening during freak periods of lag, but I have had the issue occur even when I'm sitting at 90ms, so I strongly doubt my latency has anything to do with it.

As I said, this is new with the application of patch 5.3, so I'm lead to believe it is somehow tied in with the patch. I don't know what is causing it, but let me tell you, it really really sucks when you're trying to kill Gromp at level 1 and can't Smite him because your summoner spells aren't working when they should. So please, Riot, look into this and try getting a fix out for it ASAP. It is affecting a lot of my games where little skirmishes are going in favor of the other team when a simple exhaust, heal, smite, or flash could have easily swung things in my team's favor.